You are standing at the bus stop, when you look over and see a dimly lit figure walking on a tightrope 10 feet above the ground between two small boutiques, and another walking on a broad log 40 feet above the ground between two tall trees. You are shocked. You wonder, “Who is at greater risk?” Read to the end, to see the solution to this perplexing conundrum.
But first, let’s tackle some Fact or Fiction statements, which may influence your answer:
FACT or FICTION: Malaria immunity exists.
FICTION. However, NAI or naturally acquired immunity exists. NAI acts the way some think of resistance. After repeated exposure to multiple infections, the individual’s immune system becomes more accustomed to fighting the malaria parasite, consequently reducing parasite count in the blood for subsequent infections.
When the number of parasites is lower in your blood stream, the risk of death and other severe complications of malaria is lower (e.g. cerebral malaria).
One might view this “acquired” resistance as a silver lining for the population at large in Rwanda who, aside from some few districts, experience high exposure to malaria. And, although mortality rates in Rwanda are now relatively low (under 1,000), morbidity rates and cases (4,794,778 in 2016*) are increasing, and everyone still remains at risk.
When an individual with NAI, however, moves from a high malaria exposure area to a low exposure area, their NAI can wane over time, making them more vulnerable to severe malaria.
If NAI among adults becomes compromised, the results can be catastrophic for select populations in Rwanda, not just for vulnerable populations such as children under five, pregnant women, and people living with HIV/AIDS.
FACT or FICTION: There is no malaria in the Northern Province!
FICTION. Malaria cases are lower in the North, but malaria exists, and in some cases, can be even more dangerous.
A person’s risk of severe malaria is higher in an area that experiences a lower rate of infections. In the same way high exposure areas increase levels of naturally acquired immunity (NAI), low exposure areas have the opposite effect.
“Where the risk of infection is low, almost all exposed people are at a substantial risk of debilitating or severe disease.” (Doolan)
Let’s go back to the tightrope and log walkers at the bus stop and check in with them.
Let’s say the walkers represent individuals in Rwanda; and them falling represents their risk of contracting malaria, while the distance they might fall represents the severity of their infection.
This makes for an interesting thought experiment, if someone is at low risk of contracting malaria, but has a high chance of having a severe case if they are infected, should they be more cautious than someone with a high risk of contracting malaria, but who is more likely to have a mild case if they are infected? Should they both be cautious?
As a bonus, let the person’s agility represent their individual immune system variation.
We leave the calculations up to you. We think they should both be cautious.
*"Rwanda saw more than an eight-fold increase in reported malaria cases, from 564,407 in 2012 to 4,794,778 in 2016."(Rwanda: Malaria Operational Plan FY 2019)
Doolan, D. L., Dobaño, C., & Baird, J. K. (2009). Acquired immunity to malaria. Clinical microbiology reviews, 22(1), 13-36.